SUSCEPTIBILITY OF Duponchelia fovealis Zeller (Lepidoptera: Crambidae) TO Bacillus thuringiensis BERLINER (BACILLACEAE)

Resumo

The use of biological control agents come in response to the need for a more developed and sustainable agriculture. Duponchelia fovealis Zeller (Lepidoptera: Crambidae) was reported causing serious problems for strawberry culture in the State of Espírito Santo. Because it is a recent pest, there is no registration of products for its control. Among the entomopathogen bacterium Bacillus thuringiensis Berliner stands as a promising method of control, since it is specific and is not harmful to man. This study aimed to evaluate the efficiency of two products formulated the basis of B. thuringiensis Agree® (B. thuringiensis var. aizawai GC-91) and Dipel® WP (B. thuringiensis var. kurstaki HD-1) on Duponchelia fovealis Zeller for their use in pest management programs. Bioassays were performed in microtubes containing acrylic trays, filled with artificial feed. Each tube was inoculated on the feed, 70 ml of each commercial product at a concentration 1 x 108 spores•mL-1. Subsequently, 50 larvae of each stage of development, were individually wrapped, forming a particular treatment. Mortality was assessed daily until day 7. The estimated lethal concentration (LC50) to the stage of increased susceptibility was also performed. In view of the results it was observed that the initial stage of development , showed higher mortality at 90% and 80% for Agree® and Dipel® WP, respectively products. The products were effective in controlling D. fovealis in the first stage of development, however we observed greater virulence Agree® product, which required a lower dose to achieve the LC50.